Unique spectrometers measure vertical spatial profile in addition to dispersed wavelengths. They operate in the vacuum ultraviolet (VUV) to view plasma impurity emission lines from 300 to 3200 Angstroms.
McPherson is describing new developments in short wavelength spectroscopy. McPherson one- and three-meter normal incidence spectrometers are now capable of imaging. The ability to measure both spatial and wavelength resolution is important in many applications. One example, diagnostics of impurity profile in edge plasma of large magnetically confined tokomak devices used in fusion research.
With the addition of a carefully adjusted horizontal aperture in the optical path, these spectrometers can now measure vertical spatial profile in addition to dispersed wavelengths. They operate in the vacuum ultraviolet (VUV) and view plasma impurity emission lines in the wavelength range of 300 to 3200 Angstroms. The three-meter system reports results as follows: Simultaneous wavelengths measured in a single discharge, about 37 Angstroms. With entrance slit width 0.02 millimeters, users can achieve 15.3 picometer spectral resolution FWHM. The vertical observation range can be tailored to different heights with a convex mirror. Doing so enables edge profile measurement and full profile measurements that cover an entire vertical size of the plasma.
The new spectrometers can be built for high vacuum (10E-6 Torr) and ultrahigh vacuum (10E-10 Torr). They can be equipped with microchannel plate intensifiers or sensitive CCD detectors. Other solar-blind and single-channel detectors are available for scanning applications. The instruments are delivered with precise wavelength calibration and repeatable means to set the observed vertical range. Users may choose to calibrate the sensitivity of VUV spectrometer systems using calibrated light sources and/or detectors, too.